Refinement of Steel Austenite Grain Under an Extremely High Degree of Superheating

Wang, Q.F.; Zhang, C.Y.; Xu, Wenwen; Zhao, Shuangshuang; Zhao, Xinqing; Yan, Zhang

doi:10.1016/s1006-706x(08)60072-2

Cited by 7 publications

(5 citation statements)

References 7 publications

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“…Table 3, the average grain size of the substrate is 88 nm, nevertheless, the average grain size of the white layer is 23nm, the grains in the white layer are seriously refined. The grains in white layer can be refined by rapid austenite transformation and quenching process (Wang et al, 2007), however, the nanocrystalline cannot be obtained by simple heat treatment. The researches show that the grains in the alloys can be greatly refined under high strain and strain rate (Lin et al, 2017;Sun et al, 2007).…”

Section: Methodsmentioning

confidence: 99%

White layer formation mechanism in dry turning hardened steel

Duan

Zhang

Sun

et al. 2018

JAMDSM

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The studying white layer produced in dry-hard turning process has important theoretical significance and practical value. The experiments of orthogonal turning AISI 52100 and AISI 4340 steels were employed by using PCBN inserts, a series of experimental methods were employed to study the microstructure, phase component, element segregation and hardness of machined surface. Based on experimental results, the white layer formation mechanism and the effects of cutting parameters and material properties on the white layer thickness were studied. The results show that there is ultra-fine microstructure in the white layer, the carbon segregation occurs in the machined surface and the retained austenite content is larger than that in the substrate, which indicates that the white layer is the product of phase transformation. The grains in the white layer are refined and the hardness of white layer is larger than that of the substrate, which illustrates that the plastic deformation promotes the formation of white layer. In conclusion, white layer is formed under the interaction of phase transformation and plastic deformation. The thickness and retained austenite content of white layer increase at first then decrease with cutting speed. The white layer thickness increases with feed rate, carbon content and hardness of material.

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Section: Methodsmentioning

confidence: 99%

White layer formation mechanism in dry turning hardened steel

Duan

Zhang

Sun

et al. 2018

JAMDSM

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“…Some other early works [108] [109] also reported the similar observations. However, when a very slow continuous heating is imposed and correspondingly a limited superheating achieved though, the retained austenite decomposition into the cementite or carbide can occur in an initial bainitic or martensitic steel, as in the 2.25Cr-1Mo steel for example [110], on early heating stage. This will destroy the memory effect and lead to new austenite nucleation at prior austenite grain boundaries and the precipitates on the following austenitization heating.…”

Section: Cyclic Quenching Methods (Repetitive Rapid Heating and Quenchmentioning

confidence: 99%

“…In earlier work done by Wang et al [110], they were studied the effect of extremely high degree of super heating on the refinement of steel austenite. They stated that, An extremely high degree of superheating for the reverse α → γ transformation, which was successfully performed in a initial microstructure composed of bainitic ferrite and retained austenite as a result of extremely rapid resistance heating up to an elevated austenitization temperature, can prevent restoration of the previous coarse-grained austenite and lead to the formation of an ultrafine structure during the subsequent rapid cooling.…”

Section: Cyclic Quenching Methods (Repetitive Rapid Heating and Quenchmentioning

confidence: 99%

Recent Trends in Producing Ultrafine Grained Steels

Halfa¹

2014

JMMCE

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Ultrafine grained steels with grain sizes below about 1 µm offer the prospect of high strength and high toughness with traditional steel compositions. These materials are currently the subject of extensive research efforts worldwide. Alloy design is one of the first considered issues, while designing new steel with targeted mechanical properties. However, the alloying content of steel does not fully determine the mechanical properties, but manufacturing procedure, hot rolling and cooling parameters, heat treatment parameters etc. are also of vital importance. For instance, same steel with different processing conditions can exhibit rather large variations in properties. To be precise, chemical composition with the processing parameters determines the microstructure, which in turn determines the properties of the steel. Steel is defined as an iron alloy containing C, Mn and Si that are generally used as alloying elements in steel. Micro-alloying elements such as Nb, Ti V, and B, are considered to be effective, causing strengthening as well as microstructural refinement in small quantities below 0.1 wt% (therefore these are called micro-alloy elements) and are quite generally used in ultrafine grain steel. Substitution alloying elements, such as Mo, Ni, Cr and Cu are alloyed to suppress phase transformation temperatures, i.e. for reaching certain level of strengthening, since the strength of steel structures strongly depends on the phase transformation temperature. Accordingly, the alloy design of ultrafine grains steels with different structures generally relies on: i) carbon levels, ii) sufficient alloying to obtain the desired transformation temperature and iii) micro-alloying technology in conjunction with Thermo Mechanical Controlled Processes (TMCP). Also, both advanced thermo-mechanical processes and severe plastic deformation strategies are used to produce ultrafine grained steels. Both approaches are suited to produce submicron grain structures with attractive mechanical properties. This overview describes the various techniques to fabricate ultrafine grained steels.

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“…Combining the proper chemical composition and process parameters makes obtaining different microstructures, grain sizes, and desired properties possible. Studies show that cyclic heat treatment is more effective than conventional heat treatments to optimize strength, ductility, and toughness (Ray et al, 2003;Wang, et al, 2007). The primary purpose of the cyclic processes is to reduce the austenite grain size in each cycle to ensure that the final grain size is as fine as possible.…”

Section: Introductionmentioning

confidence: 99%

Production of Nanostructured Fasteners with High Shear and Fatigue Strength for Using in Aircraft Components

GÜRBÜZ,

TAŞKIN

2023

Journal of Aviation

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Multi-axis forging (MAF) and cyclic heat treatment are among the most widely used and easy to apply grain refinement methods. In this study, microalloyed steel samples were first subjected to MAF treatments at 880° C. Microstructural analysis showed that the average grain size, which was 13.2 µm initially, decreased to 11.2 µm application of the MAF. As a second grain refinement technique, cyclic heat treatment was used. Samples were subjected to 1, 3, 5, 7 and 10 cyclic quenching. With this method, it was observed that the average grain size decreased to 2,3 µm. The mechanical tests showed that second MAF process increased the yield and tensile strength of the material about %16 while decrease the elongation only by %2. These tests also presented cyclic quenching increase tensile strength of the samples after first application.

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Refinement of Steel Austenite Grain Under an Extremely High Degree of Superheating

Cited by 7 publications

References 7 publications

White layer formation mechanism in dry turning hardened steel

White layer formation mechanism in dry turning hardened steel

Recent Trends in Producing Ultrafine Grained Steels

Production of Nanostructured Fasteners with High Shear and Fatigue Strength for Using in Aircraft Components

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